Choosing the Right Corrugated Board Grade

Single wall or double wall, which flute to use, typical weight limits and how stack height, humidity and journey length change the answer.

Board grade is the single biggest driver of both cost and damage rates. This guide gives you a plain English starting point, then the factors that shift it.

How corrugated board is built

Corrugated board is a fluted paper core glued between liners. Single wall has one fluted layer, double wall has two, triple wall has three. Liner weight is quoted in grams per square metre, so 125K means a 125gsm kraft liner.

Flute types at a glance

• B flute: around 3mm, good crush resistance, ideal for smaller retail and postal boxes.
• C flute: around 4mm, the general purpose workhorse for shipping boxes.
• E flute: around 1.5mm, thin and print friendly for small product boxes and inserts.
• BC double wall: around 7mm, for heavy or stacked loads and longer journeys.

Typical weight guidance

• Up to 5kg, short journey: single wall B or C flute, 125gsm liners.
• 5kg to 15kg: single wall C flute with heavier liners, 150gsm and up.
• 15kg to 30kg, or palletised and stacked: double wall BC.
• Over 30kg, or export and multi-handling: heavy duty double wall or triple wall.

Treat these as starting points. Always test with a sample before you commit a whole line.

What changes the answer

• Stack height: compression load comes from the boxes above, not the product inside.
• Journey length and handling: more touchpoints means more abuse.
• Humidity and cold store: damp board loses a significant share of its strength.
• Box shape: tall narrow boxes are weaker in compression than cube-like boxes.
• Product support: a product that fills the box helps carry the load. A rattling one does not.

A simple way to decide

Tell us the weight, the dimensions, how high they stack and how far they travel. We will spec a grade, make a sample and let you test it before you order.